Conventionally, there has been known an assembled battery which includes a plurality of battery cells (see JP 2013-120690 A). To be more specific, the assembled battery includes: a plurality of battery cells each having electrode terminals formed of a positive electrode terminal and a negative electrode terminal; and a plurality of bus bars which connect the electrode terminals so as to connect all battery cells in series.
In the above-mentioned assembled battery, an end portion of the bus bar, to which the positive electrode terminal of the battery cell positioned on one end of a path through which electricity flows is connected, corresponds to a positive electrode side terminal which functions as a total terminal of the whole assembled battery. On the other hand, an end portion of the bus bar, to which the negative electrode terminal of the battery cell positioned on the other end of a path through which electricity flows is connected, corresponds to a negative electrode side terminal which functions as a total terminal of the whole assembled battery.
In the above-mentioned assembled battery, the bus bar is connected (fixed) to the electrode terminal by laser welding or arc welding and hence, the bus bar cannot be easily removed from the electrode terminal. Accordingly, in the assembled battery, electricity can be always inputted to or outputted from the positive electrode side terminal (total terminal on a positive electrode side) and the negative electrode side terminal (total terminal on a negative electrode side). As a result, in the assembled battery, even when inputting or outputting of electricity is unnecessary at the time of mounting the assembled battery on an apparatus or the like, on which the assembled battery is mounted, or at the time of transporting the assembled battery, a state is maintained where electricity can be inputted to or outputted from the positive electrode side terminal or the negative electrode side terminal.
On the other hand, when the bus bar is connected to the electrode terminal by bolts or the like, the bus bar can be removed from the electrode terminal. However, when a torque generated at the time of connection by the bolts is applied to the electrode terminal frequently, there is a possibility that gas-tightness of the battery cell is affected. In view of the above, there has been a demand for a technique which can bring about a state where electricity cannot be inputted to or outputted from the positive electrode side terminal or the negative electrode side terminal in the assembled battery at portions of the battery cell except for the above-mentioned electrode terminals of the battery cell.